a. Field of the Invention
The present invention remote visual inspection systems, and in particular, concerns a flexible video monitor assembly for use with remote visual inspection systems.
b. Related Art
Remote visual inspection systems have enjoyed wide use in industrial applications and in the medical field. In industrial applications, remote visual inspection systems are used for inspecting difficult to access parts, such as the turbine blades of a jet engine enclosed in an engine housing for example. In the medical field, remote visual inspection systems (e.g., endoscopes) are used for medical diagnosis (e.g., of the gastrointestinal tract) and for visual feedback during surgery.
Remote visual inspection systems, such as flexible fiberscopes and flexible videoimagescopes for example, include an insertion tube. In industrial applications, the insertion tube may be inserted through an inspection port or a small opening of a machine. In medical applications, the insertion tube is inserted through a small incision or a body orifice. In each case, the insertion tube relays an image, received at its distal end, which is within a machine housing or a patient's body, to its proximal end, which is outside of the machine housing or patient's body.
Although one skilled in the art understands the features and operation of flexible fiberscopes (and an externally mounted image-to-video converter) and videoimagescopes (collectively referred to as "video endoscopes"), a brief description of a videoimagescope is provided below for the reader's convenience.
FIG. 1a is a side view of a flexible videoimagescope 100. The flexible videoimagescope 100 includes a body 102 and a flexible insertion tube 104. The distal end of the flexible insertion tube 104 may be articulated left and right, by means of left-right articulation control 108, and up and down, by means of up-down articulation control 112. The left-right articulation control 108 may be locked by brake 110, while the up-down articulation control 112 may be locked by brake 114. Finally, a light guide and video cable 118 permits connection to an external light source, via connector 120, and to a camera control unit, via connector 122.
The videoimagescope 100 does not have focus or diopter adjustment rings, nor does it have an eyepiece. These parts are not needed because, as alluded to above, the videoimagescope 100 provides a video output to an external camera control unit. More specifically, as shown in FIG. 1b, which is a partial cut-away, perspective view of the distal end of the videoimagescope 100 of FIG. 1a, an objective lens 150 focuses an image 158' of an object 158 in its field of view 156, onto an imaging device, such as a charge coupled device (or "CCD") 152 for example. The CCD 152 (and associated circuitry) provides a sequence of analog waveforms based on the charge accumulated in the elements of the CCD array. With flexible fiberscopes, a fiberoptic bundle relays an image from a distal end of an insertion tube to an eyepiece at a proximal end. The relayed image may then be focused, via an external mounting coupled to the eyepiece, onto an imaging device to generate a corresponding video signal. The camera control unit, mentioned above, converts the sequence of analog waveforms to frames of video, which comply with the NTSC, PAL or S video standard for example.
As is further shown in the perspective view of FIG. 1b, the distal end of the insertion tube 104 of the videoimagescope 100 includes an illumination window 132 for passing light from a light guide 130, as well as a working channel 140 terminating at port 142.
Peripheral devices, such as a video monitor, a light source, working tools, printers, video tape recorders, and other storage devices may be used to enhance the functionality of remote visual inspection systems.
Initially, the video outputs from video endoscopes were conditioned and provided to a full size video monitor. In this way, the images captured at the distal end of the insertion tube of the video endoscope are presented to the operator of the video endoscope (also referred to as an "inspector"). For example, a full size video monitor may be carried on a wheeled cart. In many inspection applications, such a presentation by a full size video monitor is appropriate. However, there are inspection applications that require a more portable video inspection system.
U.S. patent application Ser. No. 08/907,588, entitled "Portable Remote Visual Inspection System and a Case and a Peripheral Carriage Case Insert for Transporting and Storing a Remote Visual Inspection System" (referred to as "the '588 application" and incorporated herein by reference) discloses a case for transporting and storing visual inspection system components. Although the case disclosed in the '588 application greatly expands the inspection applications of video endoscopes, it does not, by itself, meet the needs of all inspection applications. For example, in the context of inspecting the turbine blades of an jet aircraft engine, the inspector might have to work from a wing of the aircraft or from atop a cowling covering which covers the jet engine. In such an inspection, the video monitor must be portable enough to be brought with the inspector.
U.S. Pat. No. 5,363,317 entitled "Control and Display Section for Borescope or Endoscope" (hereafter referred to as "the '317 patent" and incorporated herein by reference) discusses a control handle which includes a video monitor (such as a backlit LCD) and a remote steering control (a joystick) for bending or flexing the distal end of an insertion tube. The control handle terminates the proximal end of the insertion tube. Although the control handle discussed in the '317 patent increases the portability of remote visual inspection systems, it has a number of disadvantages, four of which will be discussed below.
First, the present inventors believe that inspectors will find the control handle discussed in the '317 patent to still be too large, heavy, and unbalanced. More specifically, as shown in FIG. 3 of the '317 patent, the portion of the control handle held in the palm is relatively wide so that the inspector must grasp it with a relatively open hand. This is especially problematical for inspectors with relatively small hands. The extent to which size and width of the control handle can be decreased is limited by the fact that (i) it accommodates servo or stepper motors for articulating the distal end of the insertion tube and (ii) it houses a circuit board for the joystick device.
Second, the present inventors believe that inspectors will dislike the feel of the control handle due to its center of gravity. Referring again to FIG. 3 of the '317 patent, the video monitor is relatively large and heavy. Though the servo motors are arranged in the proximal portion of the handle portion 18 to counterpoise the monitor portion, this merely locates the center of gravity near the joystick 20. (See, e.g., column 6, lines 17-21 of the '317 patent.) Referring back to FIG. 3, this means that the center of gravity will be above, or just at, the inspector's index finger thereby concentrating most of the force on the one index finger. Thus, it is believed that operation, as depicted in FIG. 3, will be necessary to minimize strain and cramping of the lower hand.
Third, the present inventors believe that some inspectors may find using the joystick awkward, and prefer the more traditional left-right and up-down articulation wheels with which they have become accustomed. For example, once again referring to FIG. 3 of the '317 patent, although the inspector can easily move the joystick 20 to the left with the bottom of their thumb pushing against the side of the joystick 20, moving the joystick 20 up, down, or right will either require the inspector to place their thumb on the top of the joystick 20 or to reposition their hand--either of which, is believed, will further fatigue the hand.
Fourth and finally, since the control handle includes both the video monitor and the remote steering control, in order to upgrade to an improved (e.g., larger, brighter, lighter and/or higher resolution) monitor, the entire system must be replaced. Moreover, since the video monitor cannot be separated from the control handle, the control handle is not useful in those inspection applications in which it is desirable (for example, to reduce weight) to have the monitor removed from the control portion of the endoscope. For example, there are instances where the video monitor is preferably not hand-held.
In view of the foregoing problems, there is a need for a remote visual inspection system which (i) may include a hand-held video monitor, which preferably has a center of gravity within (or over) the palm of the inspector's hand, (ii) is relatively light-weight, (iii) is easily to upgrade to better video monitors, and (iv) is flexible in that the video monitor may be deployed in a number of ways.